Wine

Wine, the fermented juice of the grape. Of the grape genus Vitis, one species, V. vinifera (often erroneously called the European grape), is used almost exclusively. Beverages produced from V. labrusca, the native American grape, and from other grape species are also considered wines. When other fruits are fermented to produce a kind of wine, the name of the fruit is included, as in the terms peach wine and blackberry wine.

A man harvesting grapes for Chianti wine in vineyards once owned by the Renaissance philosopher and …

Following the voyages of Columbus, grape culture and wine making were transported from the Old World to the New. Spanish missionaries took viticulture to Chile and Argentina in the mid-16th century and to Baja California in the 18th. With the flood of European immigration in the 19th and early 20th centuries, modern industries based on imported V. vinifera grapes were developed. The prime wine-growing regions of South America were established in the foothills of the Andes Mountains. In California the centre of viticulture shifted from the southern missions to the Central Valley and the northern counties of Sonoma, Napa, and Mendocino.

The introduction of the eastern American root louse, phylloxera, seriously threatened wine industries around the world between 1870 and 1900, destroying vineyards almost everywhere that V. vinifera was planted but especially in Europe and parts of Australia and California. To combat this parasite, V. vinifera scions (detached shoots including buds) were grafted to species native to the eastern United States, which proved almost completely resistant to phylloxera. After the vineyards recovered, European governments protected the reputations of the great regions by enacting laws that allotted regional names and quality rankings only to those wines produced in specific regions under strictly regulated procedures. Today, newer wine-producing countries have passed similar regulations.

Enology: scientific winemaking

Prior to the 19th century little was known about the process of fermentation or the causes of spoilage. The Greeks stored wine in earthenware amphorae, and the Romans somewhat extended the life of their wines with improved oaken cooperage, but both civilizations probably drank almost all of their wines within a year of vintage and disguised spoilage by adding such flavourers as honey, herbs, cheese, and salt water. Wooden barrels remained the principal aging vessels until the 17th century, when mass production of glass bottles and the invention of the cork stopper allowed wines to be aged for years in bottles.

In the mid-19th century the French chemist Louis Pasteur and others explained the nature of fermentation and identified the yeasts responsible for it. Pasteur also identified the bacteria that spoil wine and devised a heating method (later called pasteurization) to kill the bacteria. Later in the century, methods were developed for growing pure strains of specific yeasts in culture. Advances in plant physiology and plant pathology also led to better vine training and less mildew damage to grapes.

Mechanized innovations in the 20th century have mainly contributed to quality control. Stainless steelfermentation and storage tanks are easily cleaned and can be refrigerated to precise temperatures. Automated, enclosed racking and filtration systems reduce contact with bacteria in the air. Beginning in the 1960s, the use of mechanical grape harvesters and field crushers allowed quick harvesting and immediate transfer to fermentation tanks.

The wine grape

The thousands of grape varieties that have been developed, with 5,000 reported for V. vinifera alone, differ from one another in such characteristics as colour, size, and shape of berry; juice composition (including flavour); ripening time; and disease resistance. They are grown under widely varying climatic conditions, and many different processes are applied in producing wines from them. All of these possible variations contribute to the vast variety of wines available.

Species and varieties

Vitis vinifera, probably originating in the Caucasus Mountains, is the principal wine-producing plant, with most of the world’s wine still made from varieties of this species. V. labrusca and V. rotundifolia have been domesticated in the eastern United States, the domestication of V. amurensis has been reported in Japan, and various interspecies hybrids have been used for wine production. The high sugar content of most V. vinifera varieties at maturity is the major factor in the selection of these varieties for use in much of the world’s wine production. Their natural sugar content, providing necessary material for fermentation, is sufficient to produce a wine with alcohol content of 10 percent or higher; wines containing less alcohol are unstable because of their sensitivity to bacterial spoilage. The moderate acidity of ripe grapes of the V. vinifera varieties is also favourable to wine making; the fruit has an acidity of less than 1 percent (calculated as tartaric acid, the main acid in grapes) and a pH of 3.1 to 3.7 (mildly acid). Malic acid is also an important acid; only small amounts of citric acid are present.

A third factor attracting wine makers to this grape is its tremendous range in composition. The pigment pattern of the skin varies from light greenish yellow to russet, to pink, red, reddish violet, or blue-black; the juice is generally colourless, although some varieties have a pink to red colour, and the flavour varies from quite neutral to strongly aromatic (Gewürztraminer, Cabernet Sauvignon, Zinfandel). Some varieties, such as Pinot Noir, having rather neutral flavoured juice, develop a characteristic flavour when fermented on the skins and aged.

The species V. labrusca and V. rotundifolia seldom contain sufficient natural sugar to produce a wine with alcohol content of 10 percent or higher, and additional sugar is usually required. Their acidity at maturity is often excessive, with a low pH. Varieties of these species usually have distinctive flavours. The flavours of V. labrusca, owing to methyl anthranilate and other compounds, are considered too pronounced by some consumers. This flavour, especially prevalent in wines made from the Concord-type varieties, is commonly called “foxy.”

Cultivation

Grapes, although primarily a temperate-zone plant, can be grown under semitropical conditions. They are not adapted to the cooler parts of the temperate zone, where growing seasons may be too short to allow the fruit to reach maturity or where low winter temperatures (less than −7 °C [20 °F]) may kill the vine or its fruitful buds. V. vinifera is more susceptible to damage from winter conditions than is V. labrusca.

Climate strongly influences the composition of mature grapes. A major cause of the variation among grapes from different areas is the differing quantities of heat received by the vines during the growing season. Other important factors include differences in night and day temperature, hours of sun, and soil temperature.

Grapes begin their growth cycle in the spring when average daily temperature is about 10 °C (50 °F). To reach maturity, they require a certain amount of heat above 10 °C during the growing season. This amount of heat, called the heat summation, is calculated by totaling the number of degrees of average daily temperature over 10 °C for each day of the growing season. A heat summation of about 1,800° is required for successful growth. If the heat summation is less than required, the grapes will not ripen; they will reach the end of the growing season with insufficient sugar and too much acidity. This condition, frequently occurring in the eastern United States, Switzerland, and other cool regions, can be corrected by adding sugar to the crushed grapes. Where the heat summation is much greater than required, as in Algeria and parts of California, the grapes mature earlier and with less acidity and colour than those produced under cooler conditions.

Factors influencing the heat summation of a vineyard and, therefore, grape composition include exposure (in Europe, best from the east), air drainage (preferably from the slopes to the valley), soil temperature (above 10 °C during the growing season), and soil moisture content (not too dry at any time and not waterlogged for more than short periods).

Seasonal conditions also can be critical, especially in regions of low heat summation, as found in parts of France and Germany. When the growing season in such areas is warmer than usual, the fruit produced is riper and better balanced than is usual in cool seasons. In warm regions the sweeter dessert wines may benefit from somewhat low heat summation, resulting in less berry raisining (moisture loss) and giving the fruit better colour and acidity than is achieved when the growing season is excessively warm.

Such cultivation practices as weeding and pruning also may influence the mature fruit composition. Although the composition of the soil has an influence on soil temperature, root penetration, water-holding capacity, and vine nutrition, its effect on the quality of wine, varying from region to region, is poorly understood.

Wine regions and varieties

Almost all wines are labeled by the region of production, maturity of the fruit, variety of grape or type of wine, and year of production, and they can be further distinguished by colour, sweetness, and varietal aroma. Specific characteristics are traditionally associated with certain wines, and in many cases these traditions are guaranteed by law.

Europe

In Europe wines are primarily distinguished by the region where they are produced.

France

Most French wines are everyday vins ordinaires, of no outstanding regional, varietal, or vintage characteristics. The finest wines are entitled to the appellation d’origine contrôlée (AOC; “controlled name of origin”), which is based on a hierarchy of specific geographic areas known to produce the best wines. The largest area in the hierarchy is the region; allowing for some variation, within the regions are districts, within the districts are communes, and within the communes are vineyards, or châteaus. To receive any of these successively more rigorous appellations, wines must be produced within specific areas and must meet standards of grape variety, alcoholic content, quantity of harvest, and techniques of vine growing and wine making. Of the smaller areas, some châteaus and communes receive rankings of quality such as villages, supérieure, and grand cru (“great vintage”).

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The greatest regions of France are Bordeaux, Burgundy, Rhône, Loire, Champagne, and Alsace. Following the AOC hierarchy, Bordeaux contains such districts as Médoc, which contains the commune Pauillac, which in turn contains three grand cru châteaus. Bordeaux wines are mainly red and dry (except for those of the district of Sauternes, which are white and sweet). Primary varieties for the red wines are Cabernet Sauvignon, Cabernet Franc, and Merlot; for the white, Sauvignon Blanc and Sémillon.

Major wine-producing regions of France.

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Burgundy is smaller than the Bordeaux region. It comprises the districts of Chablis (dry white wines), Côte d’Or (red and white), Beaujolais (red), and Mâcon (white and red). The white wines are made from Chardonnay or Aligoté, the reds from Pinot Noir or (in Beaujolais) Gamay.

The Rhône region produces mostly strong, full-bodied red wines from the Syrah grape. The Loire is known for its white wines, the district of Pouilly-Fumé using Sauvignon Blanc grapes and Vouvray using Chenin Blanc. In the Champagne, legal definitions extend to the bottle-fermentation process by which the sparkling wine is produced; Pinot Noir and Chardonnay are the principal varieties. Alsace defines its mostly dry white wines primarily by grape variety, producing Alsatian Riesling, Gewürztraminer, Pinot Gris, and Sylvaner.

Wines receiving the classification vins délimités de qualité supérieure (VDQS; “delimited wines of superior quality”) must meet standards of region, variety, alcohol content, and sensory quality that result in good quality but are less severe than those of the AOC.

Italy

Known for its huge output of everyday red vini da tavola (“table wines”), Italy labels its best traditional wines as denominazione di origine controllata (DOC) or denominazione di origine controllata e garantita (DOCG). These wines must be produced in specific regions and must adhere to standards similar to the French AOC. Labels may indicate the grape variety—as in Barbera d’Alba, a red wine of the Barbera grape grown in the district of Alba in the Piedmont region.

Piedmont produces red Barolo and Barbaresco and the white, sparkling Asti Spumante. Vermouth, the flavoured dessert wine of Italy, originated in Turin, the principal Piedmontese city. From the district of Verona in the Veneto region come the red wines of Valpolicella and Bardolino and the whites of Soave. Tuscany is famous for the red wines of the various Chianti zones. Dry white Frascati wines come from the Latium region near Rome, while Marsala, the fortified wine sweetened with concentrated grape juice, comes from Sicily.

Overview of the Chianti region of Tuscany, Italy, with a detailed discussion of its wine production.

Germany

The prime viticultural areas of Germany fall into 11 regions, which are divided into districts, villages, and vineyards. A wine of better quality than the everyday Tafelwein and Landwein may receive the classification Qualitätswein bestimmter Anbaugebiete (QbA; “quality wine from a designated region”) if it is produced in a specific region and meets standards of taste and alcohol content. Sugar may be added in the production of QbA wines to make up for Germany’s short, cool growing season. Wines of the highest category, Qualitätswein mit Prädikat (QmP; “quality wine with special attributes”), must come from specific districts and be fermented from their natural sugar. The various Prädikate reflect the ripeness of the grape and, therefore, the sweetness of the wine. In order of increasing sugar content, they are Kabinett (ripe harvest), Spätlese (late harvest), Auslese (selected late harvest), Beerenauslese (selected overripe), and Trockenbeerenauslese (from berries dried on the vine).

About 90 percent of German wines are white. Riesling, Sylvaner, Müller-Thurgau, and Gewürztraminer grapes create the soft, fragrant, low-alcohol wines for which the country is famous.

Regions outside Europe

The newer wine-producing countries, lacking the centuries-old viticultural regions of Europe, emphasize the grape variety in their production of fine wines. Beginning in the 1960s, some of these countries enacted regulations guaranteeing the authenticity of these wines.

United States

Much American wine is mass-produced generic wine, often given such European-derived names as chablis, burgundy, and port. These brands must include an appellation of origin, such as California chablis, on the label.

Varietal wines may be labeled after a V. vinifera grape if the designated variety makes up at least 75 percent of the product. It must then claim an appellation of origin. If the appellation is a county, state, or even the country, then no less than 75 percent of the wine’s grapes must come from that area. If the appellation is one of the growing number of approved viticultural areas, then that area must account for 85 percent or more of the grapes. Wines may bear a vintage date if at least 95 percent of their grapes are harvested in that year.

California produces about 90 percent of American wines. The Napa Valley, Sonoma County, and other cooler areas of the north coast region produce the best wines. Cabernet Sauvignon and Chardonnay are the most prestigious, followed by Sauvignon Blanc and Pinot Noir. The Zinfandel, grown almost exclusively in California, produces a wine equal to those of the classic European grapes. California wines tend to be of higher alcoholic content and more pronounced varietal aroma and flavour than their European counterparts.

Australia

The main regions are found in an arc rimming the cooler southern states of New South Wales, Victoria, and South Australia. The Shiraz grape produces fine red wines, as does the Cabernet Sauvignon. Prominent white wines are Sémillon and Chardonnay. Sweet dessert wines are produced from Muscat and other grapes.

Grapes on the vine, in the Piccadilly Valley, Adelaide Hills, South Australia.

South Africa

Under the Wines of Origin laws, 75 percent of a varietal wine must come from the designated variety. The wine may claim one of many designated regions of origin only if all of the grapes come from that region (80 percent for fortified wines).

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Good wine, said Shakespeare, is a good familiar creature if it be well used. It has been used for at least 4,500 years. Egyptian records dating from 2500 BC refer to the use of grapes for winemaking. The first wines seem to have originated in the Middle East. There are frequent references to wine in the Old Testament. Wine was also used by early Minoan, Greek, and Etruscan civilizations. Centuries later the role of wine for sacramental use in Christian churches helped maintain the industry after the fall of the Roman Empire.